Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
H, W = map(int,input().split())
S = [input() for _ in range(H)]

Q = deque([[0,0]])
dist = [[-1] * W for _ in range(H)]
dist[0][0] = 0

while Q:
    h, w = Q.popleft()

    for nh, nw in [[h+1,w],[h-1,w],[h,w-1],[h,w+1]]:
        if 0 <= nh < H and 0 <= nw < W and S[nh][nw] == "." and dist[nh][nw] == -1:
            dist[nh][nw] = dist[h][w] + 1
            Q.append([nh,nw])

if dist[H-1][W-1] == -1:
    print(-1)
else:
    ans = 0
    for s in S: ans += s.count(".")
    print(ans - dist[H-1][W-1] - 1)